It is known to produce tires from castable elastomers, in particular from polyurethane, for example, by the spin-casting method. The production process is complicated, however, when the tire has to contain reinforcement, an essential feature in high-grade tires. In these tires, a reinforcing belt is used to reduce the peripheral increase, and reinforcement of the carcass in the cross-sectional plane of the tire is necessary to restrict the increase in width and to improve the defect characteristics of the tire, particularly in the severly stressed rolling zone. Two methods for producing reinforced cast tires have been developed, involving the use of a detachable tire core (DE-OS Nos. 2,658,374 and 2,900,565) or the assembling of the tire from separately-manufactured parts (for example DE-OS Nos. 2,224,352 and 2,651,876).
With all methods using divided cores, significant mechanical problems and expenses are involved. The production cost is even greater in the case of tires composed of separately-manufactured parts and additionally, problems may arise with these tires in the joints between the parts. The belt reinforcement is usually straightforward for a composite tire, but an effective reinforcement of the sides is difficult to produce, and in particular, a bilateral anchoring of the reinforcement on the bead wires is basically impossible.
In the case of tires in which cord threads are positioned around the core, sometimes according to a particular winding method (German Offenlegungsschriften Nos. 1,505,030; 1,605,684 and 1,301,045), special burls or ridges are required to fix these threads, removing this production method from economical viability. Another disadvantage of this method is that the core frequently buckles due to the presence of these burls or ridges in the tire.
German Offenlegungsschrift No. 1,905,930 discloses joining a reinforcing material which extends in the cross-sectional plane of the tire to the bead wires on both sides, but a variable core is required in this case.
The present invention provides an economical method for producing reinforced tires having bead rings by the casting method.